Search is full-text: It looks in titles as well as in content.
Search looks for terms, phrases, and excluded terms. For example:
brown cow (no quotes) finds all results that contain both "brown" and "cow." A result is treated as more relevant if the search terms appear together in order ("brown cow"). A result is also more relevant if it's in the object's title. The result set also includes stemmed variants, like "browned cows."
"brown cow" (quotes) finds all results that contain the exact phrase "brown cow." It doesn't find "brown cows" or "the cow is brown."
brown cow -dairy (no quotes) finds all results that contain the words "brown" and "cow" but do not contain the word "dairy."
Global search provides two types of search results: substring and keyword.
Substring search results appear in the search results pop-up and include items with names that match your search terms. In substring search results, you can click a result type, like Conversations, to view just the results for that type.
Keyword search results:
Include items with names or content that match some or all of your search terms, or variations on some or all of your search terms (like run, runs, ran, running).
Are listed by default according to how relevant they are to your search terms. You can change the sorting to date order. After changing your sort to date order, you can click the Sort by menu again, to change the sort from Descending to Ascending (to see the oldest results first).
On the search results page, you can use filters to narrow your results to just the type of items you want to see. For example, click Documents to see only the documents that were returned by your search.
After you select a filter, you can sort or further filter by the user who posted the item or the date it was posted. In the Posted By box, enter the user whose posts you want to see in the results. Select the user from the drop-down list. You can combine the Posted By filter with item type filters to narrow your results further.